This proposal addresses two questions about asthma: first, how does the pulmonary eosinophilic inflammatory response differ in ragweed allergic subjects with and without asthma? and second, what elements of the IgE-mediated inflammatory response are associated with the prolonged and ongoing pulmonary eosinophilic inflammation observed in ragweed allergic asthmatics? The hypothesized answer to both is GM-CSF. The first aim is to characterize the magnitude, kinetics and relative importance of the increased secretion of GM-CSF over a 16-day period following segmental antigen challenge. In specific aim 2, the investigators seek to define the cellular sources of the GM-CSF and in aim 3, they propose to determine whether prolonged expression of this cytokine differentiates ragweed allergic asthmatics from allergic rhinitics.